Brain perfusion and operant conditioning methods will be utilized to study the biochemical and behavioral effects of acute and chronic administration of various drugs of abuse as well as drugs which have recently proven to be effective in modifying symptoms of withdrawal from opiates. Alterations in prostaglandin levels in brain will be accomplished by directly infusing PGs and by treating subjects with prostaglandin synthetase inhibitors to determine the nature of the involvement of the prostaglandins in the action of psychoactive drugs. Drugs to be examined in detail include the cortical stimulants, and opiates, as well as clonidine. Dominant and submissive members of a paired social hierarchy will be administered phencyclidine to determine if this model of aggression is sensitive to delayed effects of this drug.